Prostheses are used to replace the function and optionally the visual appearance of a missing limb and are attached to the body of the patient. A variety of possibilities for attaching the prosthesis are known. A common possibility for attaching prostheses to extremities is the arrangement on a remaining part of the limb, the so-called stump. The stump is encompassed by a prosthetic socket, which in general is dimensionally stable. An insertion opening is formed on the proximal end of the socket, at least one fixing mechanism is provided on the distal end of the socket, on which further prosthetic components may be arranged, for example joints or other functional units such as prosthetic feet or prosthetic hands. In order to achieve a good fit, a model of the stump is prepared and the socket is adapted to the contour of the stump model. To compensate for variations in volume, it may be provided that the socket is made narrower than the molded stump model.
To increase comfort, it may be provided that a so-called prosthetic liner is arranged between the prosthetic socket and the stump. In general, the prosthetic liner comprises a closed base body with a proximal opening and is pulled over the stump in the manner of a sock. The elastic material adheres to the stump surface and generates the connection between the stump and the prosthetic socket. For attaching the prosthetic liner to the prosthetic socket, mechanical locking elements may be provided at the distal end of the prosthetic liner and corresponding locking mechanisms may be provided at the distal end of the prosthetic socket, which positively lock the prosthetic liner to the prosthetic socket after insertion into the prosthetic socket. The attachment of the prosthetic liner to the prosthetic socket can be released via an unlocking mechanism.
A further possibility for attaching a prosthetic socket to a stump resides in so-called suction socket liner technology, in which the prosthetic socket seals airtight against the prosthetic liner and the air present in the space between the prosthetic liner and the prosthetic socket is sucked or pressed out. Reverse flow is prevented by a non-return valve. It is necessary here to design the prosthetic socket in an airtight manner and to ensure a large sealing area against the prosthetic liner.
US 2011/0035027 A1 relates to a vacuum-assisted liner system with a flexible liner, which is pulled over a stump and which has at least one peripheral edge. The liner is made of an airtight material and has at least one porous region which is spaced apart from the peripheral edge, in order to enable the transport of air and moisture between an outer surface and an inner surface of the liner.
US 2012/0191217 A1 relates to a socket system with a vacuum liner for prosthetic or orthotic devices. A region of elastic material is arranged on the distal end of the closed liner, which material is harder than the material of the rest of the liner. The region has a concave section which extends inward from an outer end surface of the region. The distal region and the concave section form at least a part of a vacuum pump, in order to pump air out of the space between the liner and the prosthetic socket.
U.S. Pat. No. 8,197,555 B1 relates to a vacuum pump which is integrated into a prosthetic socket on the distal end thereof. The vacuum pump comprises an elastomer housing with two non-return valves and a spring element made from an elastomeric material. If the spring element is loaded, air is forced through a first non-return valve into an intermediary space and out of an outlet valve from the intermediary space into the environment. If the elastomeric spring element is unloaded, the outlet valve is closed and the first non-return valve is opened, and further air is sucked out of the prosthetic socket into the intermediary space. The air in the intermediary space between the prosthetic socket and the prosthetic liner is thereby pumped out.
U.S. Pat. No. 6,979,355 B1 relates to a valve arrangement for a prosthetic mechanism with a prosthetic socket, on the distal end of which is formed a channel which is closed with a valve.
U.S. Pat. No. 6,063,125 relates to an attachment mechanism for prosthetic limbs with a socket and a distal adapter, in which a through-bore is arranged. A non-return valve is formed within the bore.
DE 10 2006 054 891 A1 relates to a prosthetic socket with active air discharge, in which a pump chamber is arranged in a side wall of a prosthetic socket and is coupled via a valve to the external environment.
US 2008/0004716 A1 relates to a socket and a liner for attachment to a stump. A non-return valve is formed in the socket to transport air out of the socket.
DE 10 2004 056 775 A1 relates to a device for releasably connecting a prosthetic socket to a prosthetic lower part. A spring-loaded piston is guided in a piston chamber at the distal end of the prosthetic socket. A seal may be arranged on the piston to create a negative pressure in conjunction with a valve in the piston chamber. Elastically pretensioned latching means are assigned to the piston in order to limit the movement thereof, said latching means latching into latching recesses formed in the piston.